Real Time With Bill Maher turned into a heated debate about the religion when the host and author Sam Harris began talking about radical Islamists.
The movie star accused them of stereotyping all Muslims.
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"Hold on — are you the person who officially understands the codified doctrine of Islam?" Affleck interrupted.
He then told them their talk was "gross and racist". "It's like saying, 'Oh, you shifty Jew!'"
Harris continued to argue that Islam was currently the "motherlode of bad ideas", to which Maher agreed.
"How about the more than a billion people who are not fanatical, who don't punish women, who just want to go to school, have some sandwiches, pray five times a day and don't do any of the things that 'all Muslims do'?” he said.
“You're stereotyping. You're taking a few bad things and you're painting the whole religion with that same brush.”
Harris countered that fundamentalism wasn't limited to a few Muslims, but that there were millions.
Affleck, visibly angry, shook his head, while others intervened to argue that if Harris’ opinion was true, it was only because fundamentalists had the visible platform to espouse their ideas.
"We've killed more Muslims than they've killed us, by an awful lot... yet we're exempted from these things because they're not really a reflection of what we believe in... I'm specifically telling you that I disagree with what you think," Affleck said.